Telephone system



A. scHEuNERT TELEPHONE SYSTEM Oct. 30, 1928..

2 Sheetm l Oct. 30, 1928.

A. *sc HEYUNERT TELEPHONE SYSTEM Original Filed June 20, 1924 Def-'En'EnhE' unEJ-'I .HIT-7."

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Q wzl tovm El w26 tofu Bm w20 Patented oct. 3o, 192s.

UNITED STATES PATENT QFFCE.

ALFBEDYSCHEUNERT, OF CHARLOTTENB'URG, GERMANY, SSIGNOR T0 SIEMENS &

HALSKE AKTIENGESELLSCHAFT, WERNERWERK, 0F SIEMENSSTADT, NEAR BER- LIN,GERMANY Application led June 20, 1924, Serial No. 721,338, and inGermany July 5, 1923. Renewed. March 23, 1928.

The invention relates to a circuit arrangement for setting upconnections to private branch exchange subscribers in which a finalselector arranged for such trafiic is operated and is enabled to selecta tree outgoing line by means of switching devices which are adapted tobe placed under the control of switching devices belonging to apreceding switching stage. A

The invention more particularly concerns a development of this idea andenables the method of operating iinal selectors modified for P. B. X.working to be considerably simplified, especially in -telephone systemshaving the local traiiic separated from the toll traiiic in that atesting device is provided which is common to the switches of twoconsecutive connecting stages. Preferably this common testing device isassociated with the switch belonging to the first of these two stages.

In the examplesdaown in the drawings, comprising Figs. l-3, inclusive,the invention is applied to a system, in which the local tratic and thetoll traiiic are dealt with over separate connecting routes. t

Such a systeinis shown diagrammatlcally in Fig. 3 from which it can beseen that a call originated by a subscriber Tn is connected through,inpknown manner, over first and second local preselectors and over thegroup selectors of the different connecting stages (I to III OGW), to alocal final selector OLW. The local final selector OLW is set on thecontact of the private branch exchange MA and then starts up a group ofbackwardly hunting switches ONW, each of which is associated with anexchange line of the private branch exchange MA, these switches thenhunting for the final selector OLW that has been operated.

A toll call incoming to a toll exchange, is switched through to theautomatic exchange by the toll operator by means of the toll confnecting plug Fst and the jack KZ; andas can be seen, the connection isfurther set up over a first toll preselector FVW and over the succeedinggroup selectors of the different .connecting stages (I to III FGW) andover the toll final selector FLW to the number of the wanted P. B. X.subscriber MA. All the toll final selectors FLW are provided with ahunting switch FNW for each P. B. X. which switch is started up by thetoll fina-l selector and selects a line that happens to be freebr onlyrendered busy by a local call. The toll final selector FLW makes thetest to ascertain whether the P. B. X. lines are ree or rendered busy by`a local call and also controls the hunting movement of the succeedingtoll switches FNW.

Fig. l shows the toll final selector FLW in detail while Fig. 2 showsthe toll switch FNW located beyond the toll final selector and shows thecorresponding switch ONW located in the local route.

The circuits are based on the known earth impulse system.

It will be assumed that an incoming toll call received by way of thetoll exchange FA 0 andto be made to the P. B. X. subscriber MA connectedto the lines shown in Fig. 2 has been set up as far as the taking intouse of the toll final selector FLW (Fig. l)

The relays A and B are operated over the leads 1, 2 and 3 when the tollfinal selector FLW is taken into use by a preceding third groupselector. At the contact 4b the slow acting relay C is connected up in acircuit extending from earthover the side switch contact 5 in positionl, contact 4b and the winding of the slow acting relay C to battery. Atcontact 6c the relay C connects itself to a holding circuit notdependent on the side switch contact 5 and at its contact 7c it opens 85the test lead 3 coming from the third group selector. At the contact 80the relay C prepares a circuit for the test relay T, which' at firstremains short circuited by earth at the side switch contact 9 in thepositions 1 4. 90.

When a train of impulses is now transmitted from the toll exchange forsetting the toll final selector FLW the leads 1 and 2 are earthed inknown manner when the nger dial is rotated forwards. Hence the relay Breleases and at its contact 10b connectsup the winding I of the relay Xover the contact 11a of the energized relay A and over the side switchcontact 13 in position l. At its contact 14m the relay X prepares acircuit 100 for the vertical magnet H. During the return motion of thenumber dial the relay A releases a number of times corresponding to thenumber of impulses sent,.so that the vertical magnet is operated overthe circuit: earth, contacts b, 12a, 14m and side switch contact insition 1, and raises the switch to the desire level. At the end of thetrain of impulses the relay B is again operated over the lead 2 and-itswinding I, and at its contact 10b disconnects the relay X and at itscontact 166 closes a circuit for therelay F of the side switch extendingfrom earth over the contacts 1Gb, 17 of the side switch in position 1,the closed oil normal contact 18k, the windin of the relay F and theresistance 1910 tol attery. The side switch relay F operates and at itscontact 20j it connects u the side switch ma et S. The side switc.magnet S brings t e side switch into position 2 and at its contact 218short circuits the relay F, thereby causing it to release. The slowactin relay C holds itself over the contact 22a; w en the relay B isreleased. The next train of impulses causes the rotary inagnet tooperate in the circuit: earth, contacts 10b, 12a, 14m and the sideswitch contact 23 in position 2, hence the wipers 24, 25 and 26 of thetoll final selector FLW are rotated into engagement with the contacts 2728, and 29 belon'gin to the calling number of the P. B. X. su scriberMA, whereupon the switch shaft closes the contact 30m/7c. At the end ofthe train of impulses, the relay B is again energized over its windingI; at the contact 10b it disconnects the relay X and at the contact 1Gbit connects up the side switch relay F in a circuit which now extendsfrom earth over contact 166, the side switch contact 31 in position 2and the closed shaft contact 32u. The side switch arms are thus movedinto position 3 by the side switch magnet S in the manner alreadydescribed.

The toll operator at the toll exchange. FA

has now transmitted all the trains of impulses for positioning theswitches and for initiating the testing operation she presses a testkey, provided in known manner, whereby earth is applied to the lead 2.Hence the relay B at the toll final selector FLW is deenergized andcauses the slow acting relay X to operate over earth, the contacts 10b,11a the side switch contact 13 in position 3 and the winding I of therelay X. The relay F of the side switch is now energized over earth,contact 33?), side switch contact 34 in position 3 and contact 35a, andthe side switch moves into Pposition 4. In this position the test relayis connected over contact 360, the side switch contact 37 in position 4and the test wiper 26 and contact 29 to the testtacts 39t, 40p, 30M, theside switchcontact 41 1n position 4, wiper 25., contact 28 the lead 42,the contacts 43a and 44d and the windin of the relay R of the tollswitch FNW ig. 2) to battery. The switch FNW 1s thereby started up. Theslow acting relays V and C1 are connected up from earth over contact451', winding of the rela s V and C1, battery. The rotary magnet 1 isconnected up at the contact 461', and at contact 44d it opens theenergizing circuit of the relay R, which therefore by opening itscontact 461' again disconnects the rotary ma net D1. The wipers 47 48and 49 of the tol switch FNIV have now taken one step and have reachedfor inst-ance the contacts 50 51 and 52. The testing that now takes pace determines 'whether the switch FNW comes to rest or is moved on'stepby step in the manner above described.

A preliminary testing takes placel over the speakin lead 53 at t e sametime as the switch NW is started up; this test ascertains whether one ormore exchange lines leading to the P. B. X. subscriber are free orwhether all the lines happen to be engaged (locally or toll engaged). Acontact 5401' of a relay C1 is closed at the auxiliary local switch ONWso lon as a line is free. The relay X at the toll nal selector is lockedby its winding II in the circuit used for this preliminary test: earth,contacts 39t, 40p, 30min, winding II of the relay X, side switch contact55 in position 4, wiper 24, Contact 27, lead 53, contact- 56151,resistance 57w, Contact 5407', starting relay A'nl of the localauxiliary group of switches ONW and battery. Thus by the opening ofcontact 67 a: the side switch lis prevented from leaving the position 4.

It will first be assumed that an exchange line is free and thattherefore a contact 54er is closed. When the wipers 47, 48 and 49 of thetoll switch FNW reach the contacts 50, 51 and 52 of this line, the relayP of the toll final selector operates in parallel with the highresistance winding of thel relay Cr,

(which is normally energized when the subscribers line 83, 84, 85 isfree) the relay P being energized in the following circuit: earth,contact 360, side switch contact 37 in position 4, windings I and II ofthe relay P, wiper 26, contact 29, test lead 38, Wiper 49 of the tollswitch FNW (Fig. 2), contact 52, lead 85, and thence in known manner tobatteryT at the preselector belonging to the sul scribers line. Therelay P at its contact 58p short circuits its high resistance winding I,and at contact 40p it disconnects earth from `the driving circuit forthe toll switch FNW,

so that the switch is stopped. The relay V at the toll switch FNW (Fi 2)releases slowly, because it now remains s ort circuited at. thc contact1071', and closes its contact 59o before opening the holding circuit atthe contact 60o.

The relay T1 of the toll switch FNW is now energized in the followingcircuit: earth, battery, rotary magnet D1, wiper 61, contact 62,contacts 6301 and 591;, winding of relay T1, lead 38, Contact 29 andwiper 26 (Fig. l), winding II of the relay P, contact 58p, earth. RelayT1 (Fig. 2) switches through the speaking leads at the contacts 64151and t1, and at the contact 66251 closes a holding circuit for the relayC1. At the contact 56161 moreover the holding circuit of the relay X isopened which circuit extends over winding II as above described. Therelay'X at the toll iinal selector FLW (Fig. l) releases and closes itscontact 67 so that the side switch is caused to move on into position 5over contact 68 in position 4. The side switch beingin position 5, therelay T. (Figwl) operates, because its winding has a lower resistancethan the holding winding H of the relay P; and at its contacts 6815 and6915 switches through the speaking leads and closes its contact 7016.Hence the relay F of the side switch receives current from earth overcontact. 7 015, and the side switch contact 71 position 5, so that theside switch arms move into position 6. The relay F again receivescurrent over earth, contact 7 2p, and side switch contact 73 in position6 and by means of the magnet S moves the side switch into position 7 andover the same contacts further into position 8.

At the toll exchange the toll operator now presses her testing key inorder to call the selected P. B. X. subscriber MA, and thereby againapplies earth to the speaking lead 2. Hence the relay B releases, andcloses its c ontact 105, thereby energizing the ringing relay L overcontact lla and side switch contact 74 in position 8. At its contacts75l and 7 6l the relay L applies ringing current to the wantedsubscribers line and closes its contact 77Z, hence the operator at thetoll exchange receives a ring back tone over the windings of the relayY. Tn position 8 of the side switch ythe speaking leads are switchedthrough at the contacts 78 and 79 of the s ide switch, while the tollengaged potential, namely earth, is applied at the side switch contact8O to the test lead of the subscribers line taken into use. Owing tothis direct connection to earth, the relay P can no longer hold up andtherefore releases.

When the P. B. X. subscriber MA. answers the call by taking down hisreceiver, he closes his line loop and the feeding relay Y is energizedover both its windings, the contacts 81Z and 82Z, the side switchcontacts 78 and 79 in position 8, the contacts 68t and 691?, the wipers24 and 25, the contacts 27 and 28, the` leads 53 and 42, the contacts64t1land 65H, the wipers 47 and 48, the contacts 50. and 51 and theleads 83 and 84. The relay Y at its contact 86g closes a further holdingcircuit for the relay C and at its contact 87 g/ it opens the circuit ofthe relay A. This therefore opens the circuit to`the toll exchange sothat the operator is in known manner notified that the wanted subscriberhas answered.

.It will now be assumed that no P. B. X. line is free when the tollfinal selector FLWy is set by the last train of impulses, but that theyare all either locally or toll engaged. Hence the toll nal selector musttest for a locally engaged line with the assistance of the auxiliarytoll switch FNW, in order to render this line free for the high valuecall (toll call). As alread described the toll switch FN W was starte upand a preliminary test was performed over the lead 53 when the sideswitch was in position 4. In the present case, since no contact 5401l(Fig. 2) is now closed, a holding circuit cannot be established over thewinding II of the relay X. Hence over the contact 67m and the sideswitch contact 68 in position 4, the side switch is at once moved oninto the position 5. Tn this position the test relay P is disconnectedfrom the test lead 38, but the test relay T is connected to the testlead over the side switch contact 88 in the position 5. This relay canonly operate when the toll switch FNW reaches a contact connected toearth over a contact 98h and a resistance w90, which has a higherresistance than the relay T, that is to say when the toll switch FNWfinds a locally engaged line. If the leads 83, 84 and 85 shown in Fig. 2form' this locally engaged line, the relay T is energized over thecontact 8c and over the resistance lw91 and at contact 39 it opens thedriving circuit of the toll switch FNW and at the contacts 68t and 69tit switches through the speaking leads. Over contact t and the sideswitch contact 7]. in position 5, the side switch reaches position 6, inwhich the toll operator receives a locally engaged signal over the sideswitch contact. 92. The toll operator then notifies the B. X. subscriberMA engaged in a local call that there is a toll call for him and thatshe must therefore release his connection. She then presses the releasekey located at the toll exchange, thereby interrupting the lead l. Hencethe relay A. at the toll linal selector FL`W releases and, over earth,contacts 701i, 93a, and side switch contact 94 in position 6causes theside switch to move on into position 7. In position 7 the test relay Pis connected to the test lead 38 over earth, contact 36, and the sideswitch contact 37 in position 7 in place of the relay T, which locksitself in the before mentioned circuit. Furthermore over the side switchcontacts 95 and 96 in position 7 an opposing potential is applied to theline loop of the subscriber MA engaged in the local call, hence hisfeeding relay (not shown) at the local final selector OLVV isde-energized and the release of the local connection is brought about.Hence the contact 98h (Fig. 2) is opened and the contact 97 t is closed.The test relay P at the toll final selector (Fig. l) now operates in)nel lil() parallel with the hi h resistance winding of the relay CR ands ort circuits its high resistance winding at the contact 58p. It alsocloses its contact 72p, thus enabling the side switch to move intoposition 8. The other circuit changes are t e same as before described.

If all the exchange lines of the subscriber MA are toll engaged, neitherof the test relays P and T can operate and the side switch remains inthe position 5, in which the toll operator receives a toll engagedsignal over the side switch contact 98 and is thereby warned to releasethe connection. In response to the operators releasing the connection,the relays A and B release thus causing the relay C to be de--energizedand at its contact 99o to close a circuit for the releasemag'.- net M:this circuit extends from earth over contact 99o, side switch Contact100 in position 5 and the winding of the release magnet M to battery.Upon returning to normal the switch shaft closes the contact 101k, hencethe relay F receives current over earth, contact 990, side switchcontact- 100 in position 5, and off normal contact 101k, and the side'switch arms are moved into position 6. Over the same circuit the sideswitch is moved into position 7 and thence over contact 990 and the sideswitch lcontact 102 into positions 8 and 9. The side switch is movedfrom position 9 into position 10 over contact 990, the side switchcontact 100 and off normal contact 1017s; the relay F now again receivescurrent over earth, contact 331), and side switch contact 103; hence theside switch moves into position 11. From position 11 the side switch isreturned to position 1 over contact 990, side switch conta-ct 100 andoil normal contact 101k. When the side switch leaves position 5 thedriving circuit for the toll switch FNW (Fig. 2) is opened at the sideswitch contact 41; hence the slow acting relays V and C1 release. Therotary magnet D1 now receives impulses from earth, over the interrupterU, the contacts 10401, 62, etc., and the wiper 61, until the toll switchFNW reaches its normal position. It remains to be mentioned that in theside switch position 9, a releasing impulse is sent back from batteryover the winding II of relay B, the contact 7 o, the contact 1057, andthe contact 106vof the side switch; this impulse in known manner effectsthe release of the preceding switches.

After the connection has been established and the conversation has beencompleted, the release of the connection is brought about by hanging upthe receiver. When the subscriber MA hangs up his receiver, the relay Yreleases and at contact 86g/ it opens the circuit of the relay C. Theremainder of the releasing operation takes place in the manner justabove described.

What I claim is:

l. In a telephone system, means including a numerical switch and anon-numerical switch in serial relation for extending connections toidle linesin a group, said lines terminating in the bank ofsaidnon-numerical switch, and means' in said numerical switch fortesting said lines.

2. In a telephone system, means including a numerlcal switch and anon-numerical switch in serial relation for extending connections toidle lines in a group, said lines terminating in the bank of saidnon-numeri.

cal switch, and means in said numerical switch for controlling theoperation of said non-numerical switch to cause the latter to advanceand stop in engagement with an idleline.

3. In a telephone system, means including a numerical switch and a'non-numerical switch in serial relation for extending connections toidle lines in a group, said llines terminating in the bank of saidnon-numeri cal switch, a trunk connecting said switches, means in saidnumerical switch for operating the non-numerical switch over oneconductor of said trunk line to cause the latter to hunt for an idleline, and means in said numerical switch controlled over anotherconductor of said trunk line for rendering the said irst meansinoperative when an idle line is found. 4. In a telephone system, agroup of lines any of which may be idle, engaged in a toll connection,or engaged in a local connection, a non-numerical switch having accessto said lines, a numerical switch having access to said non-numericalswitch, means for operating said numerical switch to .connect with saidnon-numerical switch, and means in said an idle line, providing at leastone of said lines is idle,or to advance and stop in engagement with alocally engaged line if all said lines are engaged, providing at leastone of said lines is locally engaged.

6. In a telephone system,fa toll connector, a line switch accessible tosaid toll connector, a group of lines accessible to said line switch, afinder switch individual to each of said lines, local connectors, andtrunk lines connecting the banks of said finders with -the banks of saidlocal connectors.

7. In a telephone system, a group of lines,

an automatic switch having wipers, means*` for moving said Wipers intoselective relation reached for stopping the movement of said with saidlines successively, a rst test relay Wipers, and means Controlledindependent responsive when controlled over one of said of anywipers ofsaid switch for determining 10 wipers when an idle line is reached forstopwhich lof said relays is to be controlled over 5 ping the movementof saidwipers, a second one of said wipers.

test relay responsive when controlled over one In testimony whereof Iailix my signature. of said wipers when a locally engagedline is ALFREDSCHEUNERT.

